fix(auto-start) - refresh partial usage windows

[Pimpmuckl]

Summary

• poll partially consumed usage windows during the existing five-minute auto-start check
• keep login-required accounts suppressed
• guard refreshed snapshot and error writes against concurrent auth changes

Validation

• cargo fmt --all -- --check
• cargo clippy --all-targets -- -D warnings
• cargo test --all-targets -- --test-threads=1 (140 passed)
• Review Suite fast: rvw_7d61d9d6; follow-up rvw_9bc72f9c inspected and over-broad metadata CAS was removed